E11-E12 Septum dataset

This is an analysis of a dataset generated in the lab containing septum from E11.5 PGK-Cre;Rosa26YFP and E12.5 Dbx1-Cre;Rosa26Tomato embryos Cells were prepared by Matthieu Moreau & Frédéric Causeret
Libraries were generated by Matthieu Moreau & Frédéric Causeret
Sequencing was achieved at the genomics platform of Imagine
Reads were aligned on the mm10 genome to which were added: - LacZ-SV40
- Tomato-WPRE-bGH

1 Load libraries

library(Seurat)
library(dplyr)
library(patchwork)
library(cowplot)
library(ggplot2)
library(ggExtra)

library(Matrix)
library(RColorBrewer)
library(viridis)
library(wesanderson)
library(MetBrewer)


# Set ggplot theme as classic
theme_set(theme_classic())

2 Load the dataset and calculate QC metrics

2.1 Initialize a Seurat object from the raw filtered gene/bc matrix

# Load the raw filtered_gene_bc_matrix outputed by Cell Ranger
Countdata <- Read10X(data.dir = "/shared/ifbstor1/home/fcauseret/Septum/filtered_gene_bc_matrices/")

# Initialize the Seurat object
Septum <- CreateSeuratObject(counts = Countdata,
                               min.cells = 3,
                               min.features = 800,
                               project = "Septum")

Septum$Barcodes <- colnames(Septum)

dim(Septum)

## [1] 17280  5825

rm(Countdata)

2.2 Calculate percentage of mitochondrial and ribosomal counts

# Percent of mitochondrial counts
Septum[["percent.mt"]] <- PercentageFeatureSet(Septum, pattern = "^mt-")

# Percent of ribosomal counts
Septum[["percent.rb"]] <- PercentageFeatureSet(Septum, pattern = "(^Rpl|^Rps|^Mrp)")

2.3 Cell Quality according to the mitochondrial RNA percentage in the cells

# Filter cells based on these thresholds
Cell.QC.Stat <- Septum@meta.data
max.mito.thr <- median(Cell.QC.Stat$percent.mt) + 3*mad(Cell.QC.Stat$percent.mt)
min.mito.thr <- median(Cell.QC.Stat$percent.mt) - 3*mad(Cell.QC.Stat$percent.mt)
Cell.QC.Stat <- Cell.QC.Stat %>% filter(percent.mt < max.mito.thr) %>% filter(percent.mt > min.mito.thr)

Septum@meta.data$Cell.quality <- ifelse(Septum@meta.data$percent.mt > min.mito.thr & Septum@meta.data$percent.mt < max.mito.thr, "High Quality", "Low Quality")

table(Septum$Cell.quality)

## 
## High Quality  Low Quality 
##         5444          381

rm(Cell.QC.Stat, max.mito.thr, min.mito.thr)

2.4 Plot basic QC metrics

#Violin plot 
VlnPlot(Septum, features = c("nFeature_RNA", "nCount_RNA", "percent.mt", "percent.rb"), ncol = 4, group.by="Cell.quality")

2.4.1 Plot more QC metrics

# Relation between nCount_RNA and nFeatures_RNA detected with cell quality parameter
p1 <- ggplot(Septum@meta.data, aes(x=nCount_RNA, y=nFeature_RNA)) + geom_point(aes(color=Cell.quality), size=0.1) + geom_smooth(method="lm")
p1 <- ggMarginal(p1, type = "histogram", fill="lightgrey")

p2 <- ggplot(Septum@meta.data, aes(x=log10(nCount_RNA), y=log10(nFeature_RNA))) + geom_point(aes(color=Cell.quality), size=0.1) + geom_smooth(method="lm")
p2 <- ggMarginal(p2, type = "histogram", fill="lightgrey")

# Relation between nFeatures_RNA and the mitochondrial RNA percentage detected with cell quality parameter
p3 <- ggplot(Septum@meta.data, aes(x=nFeature_RNA, y=percent.mt, color=Cell.quality)) + geom_point(size=0.1)
p3 <- ggMarginal(p3, type = "histogram", fill="lightgrey", bins=100) 
    
plot_grid(plotlist = list(p1,p2,p3), ncol=3, align='h', rel_widths = c(1, 1, 1))

rm(p1, p2, p3)

2.5 Cell Cycle Scoring

# Assign cell-cycle scores
s.genes <- c("Mcm5", "Pcna", "Tym5", "Fen1", "Mcm2", "Mcm4", "Rrm1", "Ung", "Gins2", "Mcm6", "Cdca7", "Dtl", "Prim1", "Uhrf1", "Mlf1ip", "Hells", "Rfc2", "Rap2", "Nasp", "Rad51ap1", "Gmnn", "Wdr76", "Slbp", "Ccne2", "Ubr7", "Pold3", "Msh2", "Atad2", "Rad51", "Rrm2", "Cdc45", "Cdc6", "Exo1", "Tipin", "Dscc1", "Blm", " Casp8ap2", "Usp1", "Clspn", "Pola1", "Chaf1b", "Brip1", "E2f8")
g2m.genes <- c("Hmgb2", "Ddk1","Nusap1", "Ube2c", "Birc5", "Tpx2", "Top2a", "Ndc80", "Cks2", "Nuf2", "Cks1b", "Mki67", "Tmpo", " Cenpk", "Tacc3", "Fam64a", "Smc4", "Ccnb2", "Ckap2l", "Ckap2", "Aurkb", "Bub1", "Kif11", "Anp32e", "Tubb4b", "Gtse1", "kif20b", "Hjurp", "Cdca3", "Hn1", "Cdc20", "Ttk", "Cdc25c", "kif2c", "Rangap1", "Ncapd2", "Dlgap5", "Cdca2", "Cdca8", "Ect2", "Kif23", "Hmmr", "Aurka", "Psrc1", "Anln", "Lbr", "Ckap5", "Cenpe", "Ctcf", "Nek2", "G2e3", "Gas2l3", "Cbx5", "Cenpa")

Septum <- CellCycleScoring(Septum,
                             s.features = s.genes,
                             g2m.features = g2m.genes,
                             set.ident = T)
table(Septum$Phase)

## 
##   G1  G2M    S 
## 2691 1376 1758

rm(s.genes, g2m.genes)

3 Normalize counts

# LogNormalize the gene expression matrix (global-scaling normalization method)
Septum <- NormalizeData(Septum, normalization.method = "LogNormalize", scale.factor = 10000)

4 Identification of highly variable features (feature selection)

Septum <- FindVariableFeatures(Septum, selection.method = "vst", nfeatures = 2000)

# Identify the 10 most highly variable genes
top20 <- head(VariableFeatures(Septum), 20)

# Plot variable features with and without labels
plot1 <- VariableFeaturePlot(Septum) + theme(legend.position = "top")
plot2 <- LabelPoints(plot = plot1, points = top20, repel = T) + theme(legend.position = "none")
plot_grid(plotlist = list(plot1,plot2), ncol=2, align='h', rel_widths = c(1, 1))

rm(top20, plot1, plot2)

5 Scaling the data

# Linear transformation : Pre-processing step for dimensional reduction like PCA 
Septum <- ScaleData(Septum)

6 Perform linear dimensional reduction

Septum <- RunPCA(Septum, features = VariableFeatures(object = Septum))
# Examine and visualize PCA results a few different ways
print(Septum[["pca"]], dims = 1:5, nfeatures = 5)

## PC_ 1 
## Positive:  Mllt11, Tagln3, Rtn1, Tubb3, Tuba1a 
## Negative:  Hmgb2, Anp32b, Tuba1b, Dek, Phgdh 
## PC_ 2 
## Positive:  Alas2, Gypa, Car2, Acp5, Rhd 
## Negative:  Tubb2b, Pkm, Set, Map1b, Tuba1a 
## PC_ 3 
## Positive:  Fgf8, Fgf17, Serpinh1, Sparc, Zic4 
## Negative:  Alas2, Gypa, Pantr1, Car2, Efnb1 
## PC_ 4 
## Positive:  Arl6ip1, Cenpf, Ube2c, Nusap1, Prc1 
## Negative:  Ung, Pkm, Slc25a5, Mcm2, Mcm6 
## PC_ 5 
## Positive:  Cdkn1c, Hes6, Mfng, Dlk1, Rgs16 
## Negative:  Socs2, Gm3764, Wnt7b, Gas1, Thra

VizDimLoadings(Septum, dims = 1:2, reduction = "pca")

DimHeatmap(Septum, dims = 1:6, cells = 500, balanced = TRUE)

7 Determine the ‘dimensionality’ of the dataset

#  More approximate techniques such as those implemented in ElbowPlot() can be used to reduce computation time
Septum <- JackStraw(Septum, num.replicate = 100)
Septum <- ScoreJackStraw(Septum, dims = 1:20)

# JackStrawPlot
JackStrawPlot(Septum, dims = 1:20)

#ElbowPlot
ElbowPlot(Septum)

8 Run non-linear dimensional reduction (UMAP)

Septum <- RunUMAP(Septum, dims = 1:20)
DimPlot(Septum, reduction = "umap", label = TRUE, label.size = 3, pt.size = 0.1) + NoAxes()

9 Cluster the cells

Septum <- FindNeighbors(Septum, dims = 1:20)
Septum <- FindClusters(Septum, resolution = 1.5)

## Modularity Optimizer version 1.3.0 by Ludo Waltman and Nees Jan van Eck
## 
## Number of nodes: 5825
## Number of edges: 181940
## 
## Running Louvain algorithm...
## Maximum modularity in 10 random starts: 0.8266
## Number of communities: 24
## Elapsed time: 0 seconds

# Visualize clusters
DimPlot(Septum, reduction = "umap", label = TRUE, label.size = 3, pt.size = 0.1) + NoAxes() + ggtitle(paste(dim(Septum)[2], " septum cells")) 

10 Remove low quality, blood and meninges cells

DimPlot(Septum, reduction = "umap", label = TRUE, label.size = 3, pt.size = 0.1, group.by="Cell.quality") + NoAxes()

FeaturePlot(Septum, features = c("Hba-a1", "Col3a1"), order = T, 
            cols = c("grey90", brewer.pal(9,"YlOrRd"))) & NoLegend() & NoAxes()

Septum <- subset(Septum, idents = c(8, 20, 22), invert = TRUE)

DimPlot(Septum, reduction = "umap", label = TRUE, label.size = 3, pt.size = 0.1) + NoAxes() + ggtitle(paste(dim(Septum)[2], " cells after filtering")) 

11 Export files for Spring

11.1 Export raw expression matrix and gene list for spring plot generation

# Generate Spring dimensionality reduction
ExprsMatrix <- as.matrix(GetAssayData(Septum))
exprData <- Matrix(ExprsMatrix, sparse = TRUE)
writeMM(exprData, "ExprData.mtx")

## NULL

Genelist <- row.names(ExprsMatrix)
write.table(Genelist, "Genelist.csv", sep="\t", col.names = F, row.names = F)
rm(ExprsMatrix, exprData, Genelist)

11.2 Export continuous metadata

S.Score <- c("S.Score",Septum@meta.data$S.Score)
S.Score <- paste(S.Score, sep=",", collapse=",")

G2M.Score <- c("G2M.Score",Septum@meta.data$G2M.Score)
G2M.Score <- paste(G2M.Score, sep=",", collapse=",")

Percent.mt <- c("Percent.mt", Septum$percent.mt)
Percent.mt <- paste(Percent.mt, sep = ",", collapse = ",")

Percent.rb <- c("Percent.rb", Septum$percent.rb)
Percent.rb <- paste(Percent.rb, sep = ",", collapse = ",")

nCount <- c("nCount", Septum$nCount_RNA)
nCount <- paste(nCount, sep = ",", collapse = ",") 

nFeature <- c("nFeature", Septum$nFeature_RNA)
nFeature <- paste(nFeature, sep = ",", collapse = ",") 

ColorTrack <- rbind(S.Score, G2M.Score, Percent.mt, Percent.rb, nCount, nFeature)
write.table(ColorTrack, "ColorTrack.csv", quote =F, row.names = F, col.names = F)

rm(S.Score, G2M.Score, Percent.mt, Percent.rb, nCount, nFeature, ColorTrack)

11.3 Export discrete metadata

Seurat.clusters <- c("Seurat Clusters", paste0("Cluster",as.character(Septum@meta.data$seurat_clusters)))
Seurat.clusters <- paste(Seurat.clusters, sep=",", collapse=",")

Phase <- c("Phase", Septum@meta.data$Phase)
Phase <- paste(Phase, sep=",", collapse=",")

Quality <- c("Cell Quality", Septum$Cell.quality) 
Quality <- paste(Quality, sep = ",", collapse = ",") 

Cellgrouping <- rbind(Seurat.clusters, Phase, Quality)
write.table(Cellgrouping, "Cellgrouping.csv", quote =F, row.names = F, col.names = F)

rm(Cellgrouping, Seurat.clusters, Phase, Quality)

ExprData.mtx, Genelist.csv, ColorTrack.csv and Cellgrouping.csv are then used as input for the Spring App Cell coordinates of the Spring dimensionality reduction as well as doublet score are then downloaded

12 Import Spring doublet score (scrubblet) and remove doublets

doublet.score <- read.table("/shared/ifbstor1/home/fcauseret/Septum/doublet_results.tsv", header = T)
doublet.score <- filter(doublet.score, Observed_or_Simulated == "Observed")
rownames(doublet.score) <- Septum$Barcodes
Septum@meta.data$doublet.score <-doublet.score$Score
VlnPlot(object = Septum, features = "doublet.score", pt.size = 0.2) + geom_hline(yintercept = 0.4, linetype="dashed") + FeaturePlot(Septum, features = c("doublet.score"), order = T,
            cols = c("grey90", brewer.pal(9,"YlOrRd")))

Septum <- subset(Septum, subset = doublet.score < 0.4)

DimPlot(Septum, reduction = "umap", label = TRUE, label.size = 3, pt.size = 0.1) + NoAxes() + ggtitle(paste(dim(Septum)[2], " cells after doublets removal")) 

13 Import Spring coordinates

Coordinates <- read.table("/shared/ifbstor1/home/fcauseret/Septum/coordinates.txt", sep = ",", header = F)[,c(2,3)]
rownames(Coordinates) <- Septum$Barcodes
colnames(Coordinates) <- paste0("Spring_", 1:2)

# We will now store this as a custom dimensional reduction : spring
Septum[["Spring"]] <- CreateDimReducObject(embeddings = as.matrix(Coordinates), key = "Spring_", assay = DefaultAssay(Septum))

# Symmetry transform of the coordinates

Spring.Sym <- function(x){
  x = abs(max(Coordinates[,2])-x)
 }

Coordinates[,2] <- sapply(Coordinates[,2] , function(x) Spring.Sym(x))

Septum[["Spring"]] <- CreateDimReducObject(embeddings = as.matrix(Coordinates), key = "Spring_", assay = DefaultAssay(Septum))

rm(Coordinates, doublet.score)


# Spring visualization 
DimPlot(Septum, reduction = "Spring", pt.size = 0.2, label = T, label.size = 3) + NoAxes() + NoLegend()

FeaturePlot(Septum,
            features = c("Eomes", "Tbr1", "Isl1", "Trp73", "Onecut2", "Dbx1", "dtTomato", "Pcdh8", "Spon1"),
            reduction = "Spring",
            ncol = 3,
            order = T,
            cols = c("grey90", brewer.pal(9,"YlGnBu")))  & NoLegend() & NoAxes()

14 Save object

saveRDS(Septum, "/shared/ifbstor1/home/fcauseret/Septum/Septum.RDS")

15 Session Info

#date
format(Sys.time(), "%d %B, %Y, %H,%M")

## [1] "09 April, 2022, 19,11"

#Packages used
sessionInfo()

## R version 4.1.1 (2021-08-10)
## Platform: x86_64-conda-linux-gnu (64-bit)
## Running under: CentOS Linux 7 (Core)
## 
## Matrix products: default
## BLAS/LAPACK: /shared/ifbstor1/software/miniconda/envs/r-4.1.1/lib/libopenblasp-r0.3.18.so
## 
## locale:
##  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
##  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
##  [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
##  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
##  [9] LC_ADDRESS=C               LC_TELEPHONE=C            
## [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       
## 
## attached base packages:
## [1] stats     graphics  grDevices utils     datasets  methods   base     
## 
## other attached packages:
##  [1] MetBrewer_0.2.0    wesanderson_0.3.6  viridis_0.6.2      viridisLite_0.4.0 
##  [5] RColorBrewer_1.1-2 Matrix_1.3-4       ggExtra_0.9        ggplot2_3.3.5     
##  [9] cowplot_1.1.1      patchwork_1.1.1    dplyr_1.0.7        SeuratObject_4.0.4
## [13] Seurat_4.1.0      
## 
## loaded via a namespace (and not attached):
##   [1] Rtsne_0.15            colorspace_2.0-3      deldir_1.0-6         
##   [4] ellipsis_0.3.2        ggridges_0.5.3        rstudioapi_0.13      
##   [7] spatstat.data_2.1-2   farver_2.1.0          leiden_0.3.9         
##  [10] listenv_0.8.0         ggrepel_0.9.1         fansi_1.0.2          
##  [13] codetools_0.2-18      splines_4.1.1         knitr_1.37           
##  [16] polyclip_1.10-0       jsonlite_1.7.3        ica_1.0-2            
##  [19] cluster_2.1.2         png_0.1-7             uwot_0.1.11          
##  [22] shiny_1.7.1           sctransform_0.3.3     spatstat.sparse_2.1-0
##  [25] compiler_4.1.1        httr_1.4.2            assertthat_0.2.1     
##  [28] fastmap_1.1.0         lazyeval_0.2.2        cli_3.2.0            
##  [31] later_1.3.0           htmltools_0.5.2       tools_4.1.1          
##  [34] igraph_1.2.11         gtable_0.3.0          glue_1.6.2           
##  [37] RANN_2.6.1            reshape2_1.4.4        Rcpp_1.0.8.3         
##  [40] scattermore_0.7       jquerylib_0.1.4       vctrs_0.3.8          
##  [43] nlme_3.1-153          lmtest_0.9-39         xfun_0.30            
##  [46] stringr_1.4.0         globals_0.14.0        mime_0.12            
##  [49] miniUI_0.1.1.1        lifecycle_1.0.1       irlba_2.3.5          
##  [52] goftest_1.2-3         future_1.23.0         MASS_7.3-54          
##  [55] zoo_1.8-9             scales_1.1.1          spatstat.core_2.3-2  
##  [58] promises_1.2.0.1      spatstat.utils_2.3-0  parallel_4.1.1       
##  [61] yaml_2.2.2            reticulate_1.22       pbapply_1.5-0        
##  [64] gridExtra_2.3         sass_0.4.0            rpart_4.1-15         
##  [67] stringi_1.7.6         highr_0.9             rlang_1.0.1          
##  [70] pkgconfig_2.0.3       matrixStats_0.61.0    evaluate_0.14        
##  [73] lattice_0.20-45       ROCR_1.0-11           purrr_0.3.4          
##  [76] tensor_1.5            labeling_0.4.2        htmlwidgets_1.5.4    
##  [79] tidyselect_1.1.1      parallelly_1.30.0     RcppAnnoy_0.0.19     
##  [82] plyr_1.8.6            magrittr_2.0.2        R6_2.5.1             
##  [85] generics_0.1.1        DBI_1.1.2             withr_2.4.3          
##  [88] mgcv_1.8-38           pillar_1.7.0          fitdistrplus_1.1-6   
##  [91] survival_3.2-13       abind_1.4-5           tibble_3.1.6         
##  [94] future.apply_1.8.1    crayon_1.5.0          KernSmooth_2.23-20   
##  [97] utf8_1.2.2            spatstat.geom_2.3-1   plotly_4.10.0        
## [100] rmarkdown_2.11        grid_4.1.1            data.table_1.14.2    
## [103] digest_0.6.29         xtable_1.8-4          tidyr_1.1.4          
## [106] httpuv_1.6.5          munsell_0.5.0         bslib_0.3.1

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1. IPNP & Imagine Institute, Paris, France, frederic.causeret@inserm.fr↩︎